Purpose: Context is increasingly recognized as a key factor to be considered when addressing healthcare practice. This study describes features of context as they pertain to knowledge use in long-term care (LTC). Design and Methods: As one component of the research program Translating Research in Elder Care, an in-depth qualitative case study was conducted to examine the research question "How does organizational context mediate the use of knowledge in practice in long-term care facilities?" A representative facility was chosen from the province of Saskatchewan, Canada. Data included document review, direct observation of daily care practices, and interviews with direct care, allied provider, and administrative staff. Results: The Hidden Complexity of Long-Term Care model consists of 8 categories that enmesh to create a context within which knowledge exchange and best practice are executed. These categories range from the most easily identifiable to the least observable: physical environment, resources, ambiguity, flux, relationships, and philosophies. Two categories (experience and confidence, leadership and mentoring) mediate the impact of other contextual factors. Inappropriate physical environments, inadequate resources, ambiguous situations, continual change, multiple relationships, and contradictory philosophies make for a complicated context that impacts care provision. Implications: A hidden complexity underlays healthcare practices in LTC and each care provider must negotiate this complexity when providing care. Attending to this complexity in which care decisions are made will lead to improvements in knowledge exchange mechanisms and best practice uptake in LTC settings.